1. Technical Field of the Invention
The present invention relates generally to DCxe2x80x94DC converters and voltage regulators, and more specifically to a multi-phase DCxe2x80x94DC converter having redundant DCxe2x80x94DC phases or modules isolated by short protection mechanisms.
2. Background Art
FIG. 1A shows a simplified example of an electronic system 5 according to the prior art. The system is powered by an AC source 6, to which is connected an AC-DC converter 7. One component of a DC-powered electronic system which is known to be subject to various types of failures, is the DCxe2x80x94DC converter 8, whose primary function is typically to step the DC voltage down from e.g. 12 volts provided by the AC-DC converter to 5 volts or 3.3 volts or whatever is required by the particular load 9 for which the system is designed. Therefore, in previous systems it has been known to provide a redundant or duplicate DCxe2x80x94DC converter 10 in parallel with the primary DCxe2x80x94DC converter 7. This is commonly known as xe2x80x9cN+1 redundancyxe2x80x9d. Unfortunately, this seldom-used protection has meant doubling the cost of the DCxe2x80x94DC converter portion of the system.
FIG. 1B shows an exemplary DCxe2x80x94DC converter 8 (or 10), such as may be used in the system of FIG. 1A. The DCxe2x80x94DC converter 8 includes a duty cycle controller 11 which provides duty cycle control signals SG2 and SG3 to respective switches Q2 (xe2x80x9ctop switchxe2x80x9d) and Q3 (xe2x80x9cbottom switchxe2x80x9d) of a synchronous multi-phase buck regulator 12. The top switch Q2 is often called a pass switching element, and the bottom switch Q3 is often called a synchronous switching element. The output of the regulator 12 is taken from the switch node between the two switches, and is fed to an inductor L1 which stores energy and feeds into a diode DO which prevents current from returning into the regulator from the load. The inductor L1 and capacitor C1 smooth the provided voltage and amperage over time. A capacitor C2 is coupled across the load to assist the regulator by providing current in response to changing demands from the load.
James Dinh is co-inventor of the present invention and is the inventor of a related invention disclosed in U.S. Pat. No. 6,262,566 xe2x80x9cDC-to-DC Controller Having a Multi-Phase Synchronous Buck Regulatorxe2x80x9d which issued Jul. 17, 2001. Both this patent and that one are assigned to Intel Corporation.
FIG. 2 shows a simplified, exemplary electronic system according to the ""566 patent. In that system, the DCxe2x80x94DC converter is split into multiple phases 1-M (elements 21 to 24), which are controlled by a multi-phase controller 26. In general, the phases 1-M are out of phase with each other. Each DCxe2x80x94DC phase contributes to the overall output current provided to the load. The multi-phase controller sequences the phases to reduce ripple at the input and the output.
In the system of FIG. 1A, if the main DCxe2x80x94DC unit 8 fails, the N+1 redundant DCxe2x80x94DC unit 10 is there to continue powering the load. In the system of FIG. 2, if any of the DCxe2x80x94DC phases fails, either the load will be underpowered, or the remaining DCxe2x80x94DC phases will have to work harder to make up for the lost DCxe2x80x94DC phase(s). This may lead to premature failure of the overall DCxe2x80x94DC system, as the surviving DCxe2x80x94DC phases may have to work beyond their design parameters. In some cases, loss of one or more DCxe2x80x94DC phases may even result in a domino effect that takes down the other DCxe2x80x94DC phases, resulting in a loss of power to the load, or perhaps even destruction of the load.
If one were willing to bear the cost of doubling-up the DCxe2x80x94DC componentry, one could impose the FIG. 1A N+1 thinking on the FIG. 2 system, and have two complete sets of DCxe2x80x94DC converter 20 in an N+1 redundant system.
The present invention, however, offers a more insightful, efficient, and inexpensive solution.